Telephone system



Jan. 2, 1940. D. B. RBlsoN TELEPHONE SYSTEM Filed Jan. 4, 1936 ,Zwe nov:DAN/EL Ro/s o/v vg Harn/ey.

Patented Jan. 2, l1940 y STATES gPMEnir ortica `jv l l(2,185,521TELEPHONE SYSTEM' y yDaniel B. Robison; Oak Park, Ill., assignorfv toKeli logg`Switchboard Land Supply Company, Chiv cago, Ill., acorporation of Illinois npplieatiunsmnuary 4, 1936., seriarNo. 57,497 Al Y 9 claims@(ci.179-36)` This invention relates totelephone ysystemsandl relates more particularlyl to those typesof 'telephone systems whichcomprise a -main liney extending from a main station to which areccnnected a plurality of 'branch lines yeach leading toseveralstations.v

Systems of thistype have rbeen in use for some time in remote regions,such as national Aparks or` the like, for the reporting of iires by theforest rangers. They yusually comprise a main staytion which `is therangers headquarters and a main' lineextending therefrom.A To this mainline are conneetednuinerous branch lines to each of whichare connected avnumber oftelephones l located at look-out stations. y 1

The telephone vsets locatedat the respective look-out stations can-beused to "call-the main station only for the reporting of a re or lanyroutineI report and cannot be connected to another station on anotherbranch line unless vboth stations signal the main station at the sametime.A

One of the problems in systems ofithis kindy has been the maintenance ofthe efficiency of the system shouldsome accident take place on one ofthe branch lines. Often in systems of this kind an accident on onebranch line-prevented any' ofl the stations on any ofthe other branchlines from signaling the-main station, dueto the ,Y Ifact that groundsand shortircuits on the l a branch line` in trouble vwould"absorball theringing fc'urrent from the callingstation on the other branch line.

v Another diiculty' arose When a large ynumber v of branchlines wereconnected tothe mainline 35 y y in which case the line resistance becameso great that y'all the ringing current from the calling.

station-was absorbed in the line 'and the signall at the main stationwasnot operated.`

'- My invention hasfoverccme these diiiiculties -by providingy means forconnecting and disconnectf ing a branch line to'andf-rom the main line`wlnen'it -is desired to lplace ,aV call 'at vthe main station. i

A feature of my 'switching' means at the junction lof a,y branch lineyand main line for connecting and disconnecting the two lines. f

v "Another feature of' my invention -isfthe profv visionof means at'thebranch station for oper-` ating the switching-'means ,at a remotepoint. y "Other features will ,become apparent from a p'ersual of thefollowingv specification and claims taken in connection' with" thevdrawing which illustrates schematically the telephone system of myinvention. l

- tion points JP.

invention is the provision ofl Referring more particularly 'to' thedrawing, the

part at theextrerne'left marked look-out .sta-e"r tion comprises theusual magneto ytelephone substation'fequipment, includinga transmitterT,

receiver R, hooksWitch HS, local battery LB, inr` duction coil IC,ringer-RG,and hand generator HG. A push button PB vvis also provided. Al

branch line shown in dotted'lines connects the telephone set located atthe look-out station LS tothe junction oithefmain line and the branchThe apparatus at the junctionv point JP comprises an `alternatingcurrent relay AC anda disconnect-ing alternating current relayl DAC, atrip relay TR which connects the branch line con ductors -to theymainline conductors, and a re` storing relay RR.` Retard coils ARC andBRC serve to balance the two sides of lthe line and to prevent anylosses vduring the transmission `are connected across the lineconductors and period. Thejourre'nt .supply for the relays is furvnishedfrom a single non-grounded battery which is shown as separate batteriesyfory the purpo'seof convenience.

The main line-conductors ML extend from the junction point JP to themain station MS Where they terminate in contacts of ajack J. Adrcpsignal Dis also vprovided at the main station.` The mainline ML mayAalso Abe manymiles .inv-

length'and pass through numerous other junc- The operation'oi the systemis asffollows: Should an attendanty `at the look-out stationLS desirea'connectionl With a main station MS he will turn thelcrank oi thehandgenerator HG which causes alternating currentfto be impressed uponboth sides of the line in series with the ale* ternating current relayAC located-atl the junction point JP, which relay isfoperatedv by this`currentA flowing from thecontactl tof the gen erator HG, conductor 2,.branchl line BL, the

Winding of the alternating current relay AC,

branch line BL, normally'closed contactr 3, push button PB, conductor A,to the hand generator HG. The-relay ACoperate's and closes its con#-tactv5 to establish an obvious .energizing circuit v for the trip relayTR, which l'closes its alternate contacts 8 and 'l to'comiecty thebranch line con-` oluotors to the main line conductorsMll.. vA lockingmember 8holds the contacts 6 and i of relay TR in their alternateposition after the re'- lay TR/haslrestored due "-to the opening ofthecontact 5 upon the restoration of the relay ACv after the application ofringing current to the branch line from the generator HG has stopped. f

However, the attendant at the look-out station LS again operates thehand generator to apply ringing current over the branch line BL, throughthe juncture point JP, and the main line NEL to operate the signal ordrop D located at the main station MS. This current can be traced fromcontact I of the hand generator HG, conductor 2, branch line conductorBL, conductors 9 and I0, alternate contacts 6 of TR, main line con'ductor ML, closed jack contact Il, through the winding of the dropsignal D, closed jack contact I2, main line conductor ML, alternatecontact B of relay TR, conductor I3 branch line conductor BL, normalContact 3 of push button PB, conductor 4 to the other side of thegenerator HG. Current owing through the winding of the drop signal DSactuates the signal to inform the at-` tendant at the main station thata call has been' 'made bysome look-out station.

After operating the hand generator HG the attendant at the look-outstation LS removes the receiver R from the hoolrswit'chI-IS and therebyconnects, the telephone transmitter and receiver to the jack at ,themain station over the circuit previously described for the ringingcurrent.

After the conversation is terminated the at-l tendant at the station LSrep-laces the receiver R upon the hookswitch HS and thereby disconnectsthe telephone apparatus from the line. He next operates the push buttonPB and cranks the hand generator HG to place grounded gen erator currenton both sides of the branch line BL. rThe disconnecting alternatingcurrent relay DAC is operated by this current over a circuit Whichcan betraced from ground at `alternate contact 3 of push button PB,`conductor-4, through the hand generator HG and. contact l, conductor 2,to the contact i4 of push button PB. At this point the current divides,part of it passing through conductor l5, branch line conductor BL,conductor ,9, retard coil ARC, through the winding of the disconnect`relay DAC to ground, the other half of the current proceeding throughalternate contact 'i6 ofpush button PB, conductor l'i, branch lineconductor BL, normal contact i8 of relay AC, through the retard coil BRCand the Winding of relay DRC to ground The alternating current` relay ACis not operated by this current as it has'ground potential on each sideof its winding. The relay DAC operates and closes its alternate ,contactI9 to establish an obvious energizing circuit for the restoring relay RRwhich relay operates and movesthe locking member 8 to permit the con.-tacts -6 and 7 of relay TR to restore to normal andv thereby disconnectthe branch line from the main line conductors. l

My invention thus provides a cheap and er1-lcient system which permitsthe ready connectio-n of a branch. magneto telephone', line to a mainline leven, though the calling station is located at a point remote fromthe junction of the two lines and also provides for the disconnectionlof the branch line from the main line at allv times, except during therelatively short time when conversation is taking place.' Thus theefficiency of the telephone system is greatly in creased as trouble onone particular branch line Letters Patent is; l

1 1. A telephonesystem comprising a' main line, i

no limitations upon my invention other vthan `thoseimposed ,by the scopeof claims.

is new and desire to secure by United a main station onrsaid line, aplurality of branch vlines associated therewith at junction points"remote fromv said main station, a station on'Y the appended.

` tain particular embodiments alterations Vand l modifications may bemade thereto and I- intend eachi'of said branch lines, a signal at saidmain station, relay means at said junction points for connecting saidbranch lines `to said main line, signaling means at said branch linestationsfor rst operating saidconnecting means at 'said/l` .n junctionpoints and for then operating said `sig.

nal at said main exchange.

v2.`;A telephone system comprising a Imain line,V`

a` main` station on saidline, a plurality .of branch lines associatedtherewith at junction pointsre;

mote from said main station, a station on .each

of' said branch lines, a signal at said. main sta.-

tion, relay means at said junction .points'orH connecting saidbranchlines tosaid mainline', signaling means at said branch linestati-onsfor first operating said connecting means vat said junctionpoints and for then operating'said signal at said main station, andfurther meansv at said branch line station Iforrestoring saidconnectingmeans at said, junction point.

3. A telephonesystem comprising-@maidmi@ and a branch line, a junction`point for) said lines, a station on said mainline, saidjunction pointbeing remote from said line station, a' signal at said main linestation, a station on said. branch line,v relayy means atsaidjjunction-point for connectingsaid branch line vto fsai'd mainy fline and for disconnecting said lines, signaling means at said branchline station foroperating said relay means to connect said lines, foroperating said signal athsaidmain station, and for operatingsaidrelayvmeans to disconnect-said;

linesl ,l fl., A telephone system comprising a main line and a branchline, a junctionpoint for said lines, a station lonsaidbranch line, afstation on said main line, said junctionwp-oint being: re-f mote fromsaid mainline station, asignalat said main linestation, relayv means .atsaid junction, point for connecting Said 'branch liney ftosaid main lineand for disconnectingisaid lines, sigvnaling means includinga source ofcurrent at said branchlline station fo-roperatingsaid relay meanstorconnect said `li nes,;for operating said' signal at said mainstation,4 and-for operating said relay means to disconnect-said lines.5. A- telephone system comprisinga mainline and abranch line, .a.junction point for saidv lines, a station on said branch line.;signaling means includinga source of alternating current at said branchline station, :relay means at said junction point `comp-rising a relayliar/ingv f 'contacts for connectingvsaid branch` line to said main lineandan alternating current relayA rel,-

spons'ive to vsaid signaling means for controlling.

said connecting relay, a'second alternating current relay responsivetofsaidsignalingmeans rand and a disconnect relay, controlledv by saidsecond; alternating current relay, for restoring the contacts of saidconnecting relay to disconnect said branch'line-vfrom said mainline;Y

6. A telephone system comprisinga mainsta;LA tion, a main line extendingtherefrom', a plural,`

cof

ity of junction points located at separated posi-v disconnecting saidbranch line from said main tions along said main line, branch linesextending from said junction points, respectively, a branch station'oneach'of said'branch lines, a source of current at each of said branchstations, means at each branch station for projecting current from saidsource over the two conductors of said branch line in series, means atthe junction y point of each branch line responsive to the flow l ofcurrent over its conductors in series for connecting said branch line tosaid main line, means` of junction points located at separated positions,Y

along said main line, branchlinesjextending from said junction points,respectively, a branch station on each of said branch lines, a source ofalternating current at each of said branch stations, means at eachbranchvstation .for projecting current from said source over the twocon-y ductors of its said branch linev in series, means' at the junctionpoint ofr each branch line responsive to flow of current over its twoconductors in series for connecting said branch line to said main line,mechanical means for maintaining said connection, means vat each saidbranch station for projecting current from said source over the twoconductors. of its said branch line, in parallel, and means responsiveto the flow of currentover said conductors, in parallel, for

line. l f

8. A telephone system comprising a main station, Va main line extendingtherefrom, a junction point located on said main line, a branch lineextending from said junction point, a branch station on said branchline, a source of current at said branch station, means at said branchstation for projecting current from said source over the two conductorsof said branch line in series, means responsive to said current forconnecting said branch line to said main line, means for maintainingsaidconnection, means at said branch station for projecting current fromsaid source over the two conductors of said branch, in parallel, andmeans responsive to the iiow ci current over said conductors', Vinparallel, for disconnecting said branch line from said main line. y

9. A telephone system comprising a main staltion, a main line'extendingtherefrom, a junction point located on said main line, a branch lineextending from said junction point, a branch station on said branchline, a source of current at said branch station, means at said branchstation `for projecting current from said source over the two conductorsof saidy branch line in series, means responsive to said current forcon- '.necting vsaid branch line to said main line,vme

chanical means for maintaining said connection, means` at said branchstation for projecting current from said source over the two conductorsof said branch line, in parallel, and means responsive to the flowl ofcurrent over said' conductors, in parallel, for disconnecting saidbranch line from said main line. i

, DANIEL B. ROBISON.

